Vectoring is to navigationally guide an aircraft in flight by air traffic control (ATC) issuing appropriate headings, based on the use of an air traffic service (ATS) surveillance system (usually radar). The air traffic controller (ATCO) decides on a particular airfield traffic pattern for the aircraft to fly, composed of specific legs or vectors. Aircraft vectoring is used under special circumstances only, such as to vertically separate aircraft by a specified distance in densely traveled airspace. Vectoring is primarily used in the terminal environment where the aircraft is in close proximity to the ground. In other circumstances, vectoring may be used at a considerable altitude above the terrain.
The Minimum Vectoring Altitude (MVA) is the lowest altitude level to which ATCO may issue aircraft altitude clearances during vectoring, except if otherwise authorized for radar approaches, departures, and missed approaches. MVAs meet obstacle and terrain clearance requirements in the airspace within the maximum displayable range of the ATC radar system. MVA charts are developed for geographic areas near airports where there are numerous minimum altitude requirements due to variable terrain features and/or obstacles (collectively, “obstructions”). The responsible ATC facility determines the MVA chart design based on topography, obstruction data, and operational requirements in accordance with governmental regulations. The geographic area is subdivided into vectoring altitude sectors, each vectoring altitude sector having a designated MVA. While a MVA chart assumes a roughly circular shape, the MVA chart may be complicated because there is no prescribed limit on the size, shape, or orientation of the vectoring altitude sectors. Each vectoring altitude sector is large enough to accommodate the vectoring of aircraft therein at the MVA. Overall, the vectoring altitude sectors are designed with consideration of aircraft maneuvering ability, obstacle clearance requirements, and air traffic flow requirements. Each vectoring altitude sector boundary is at least a prescribed number of miles from the controlling obstruction used to determine the MVA in that vectoring altitude sector. In order to avoid cases of large altitude sectors with an excessively high MVA because of isolated prominent obstacles, the isolated obstacle or group of obstacles may be enclosed in an obstacle buffer area with boundaries that are a designated number of miles from the controlling obstruction(s). MVAs can be, and often are, below Minimum Safe Altitudes (MSAs).
MSAs are altitude levels that are also intended to ensure clearance over obstacles and terrain within a particular geographic area proximate to a route that an aircraft may travel during flight. The geographic area associated with MSAs is subdivided into safe altitude sectors. A portion of the MVA and MSA geographic areas may overlap. MSAs are often determined based on criteria provided by a governmental or regulatory organization. For instrument-based operations in accordance with instrument flight rules (IFR), MSAs are often published on aeronautical charts (known as MSA approach plates) for various airways, routes, and approaches for a given navigation reference point, and are provided to pilots. Pilots may also be provided with MSA or TAA information (collectively referred to herein as “MSA information”) on display devices in an aircraft such as described in U.S. Pat. No. 8,032,268 issued Oct. 4, 2011 by the same named assignee, and incorporated by reference herein in its entirety. Unfortunately, MVA charts are not usually provided to flight crews on the flight deck. In addition, pilot reliance on conventional MVA charts would significantly increase cockpit workload because, in the event of a vectoring instruction, a pilot would have to interpret the MVA chart quickly during a period of high stress to gain critical MVA information. Furthermore, if conventional MVA charts were combined with MSA information on a display device, the resulting display would be confusing, with a tangle of sector lines and radials.
Therefore, while a pilot may be issued vectoring instructions that involve descending to an altitude that the pilot knows to be below the MSA (e.g., from a MSA approach plate), the pilot cannot independently verify that the altitude is above the MVA. The pilot has to rely solely on the ATCO who may have disregarded or been incorrect about the MVA. Moreover, that the pilot cannot independently verify that the altitude is above the MVA is the antithesis of the cross-checking processes that are critical in aviation. In addition, while the ultimate responsibility for the safety of the aircraft rests with the pilot who can refuse aircraft altitude clearances and vectoring instructions, the pilot does not have the necessary MVA information to know whether to refuse. As a result, the potential for obstacle and terrain avoidance when vectoring below the MSA may be compromised.
Accordingly, it is desirable to provide aircraft flight deck displays and systems and methods for displaying integrated minimum vectoring and safe altitude information on the display device in an aircraft. It is desired that the pilot may quickly and easily verify the MVA in the altitude sector in which own aircraft is located, thereby increasing pilot situational awareness, the potential for obstacle and terrain avoidance, and improving flight safety.